Fluid pressure power system



Dec. 19, 1939. H. A. CENTERVALL,

' I FLUID PRESSURE POWER SYSTEM Filed Feb. 13, 1936 2 Sheets-Sheet 1 INVEN TOR #0 0 14. CE/{TEFVILL B d m, Mm

ATTORNEY-J -19,1939. HA. C NTERVALL 2,183,541

FLUID PRESSURE POWER SYSTEM Filed Feb. 13, 19 36 2 Sheets-Sheet 2 Hugo,4. CENT'RIlLL BY flmu IM ATTORNEYS Patented Dec. 19, 1939 ManlyCorporation, New York,

poration of Delaware N. Y., a cor- Application February 1a, 1936.Sei-ialNor 63,712

Claims.

This invention relates to fluid power systems and some of its featuresare particularly suited for use with the type oi fluid power system inwhich a closed fluid circuit is employed. Fluid 5 circuits of this typeare frequently used in hydraulic variabiespeed transmissions, and forpurposes of illustration I have accordingly shown f the presentinvention as applied inconnection i with a fluid device of thischaracter.

,transmission requires that its closed circuit be kept completely fllledwith fluid at all times and that the temperature'ofj the working fluidbe held within certain ranges to prevent overheating. Experience hasalso shown that devices of this character operate most satisfactorilywhen back pressure is maintained-inthe low pressure or return portion ofthe main fluid circuit. .Iti's also of the greatest importance that the-m fluidused in a machine of this class be free from dirt, grit andother foreign matter as these will cause cutting or bindingof the partswhich are necessarily closely. fitted Even careful straining of thefluid does not remove all very fine particles, and other foreign matter,such as'dirt, small particles of metal, etc., will frequently be addedto the circulating fluid while'the machine is oper-' ated. It istherefore advantageous. to employ some means for effectively andcontinuously cleaning the fluid 'to prevent injury to the machine andtosecure'best operating results. An object o! the invention is to provideim- 1 proved means for replacing the fluid which leaks is keptcompletely filled and for maintaininga predetermined pressure of thefluid in the low pressure portion of the main fluid circuit. Anotherobject of the invention is to provide meai'is for continuously chan vthe fluidcontained in 40 the otherwise closed main fluid circuitand forI overcoming/the tendencyto overheat. A further object of the. inventionis toprovide means for cleaning the working .fluid which is'employed.Other and more specific objects. will appear fromthe followingdescription ofan illustrative embodiment of the present invention. Inthe drawings: T ,7 Fig.1 is'a side elevation, partly in section andpartly schematic, showing thepresent invention as applied inconnectionwithanhydraulicyarlable'speed transmission. 4 Fig.2 is ,an enlargedview, paitlyin section alongthe 11ne.z 2 to Fig. l, andpartly-schematic, showing the arrangement of parts and certain details,of construction, and Fig. 3 shows in dia- Proper and eflioient operationof a. hydraulic out "or. the main fluid circuit so that said circuitshown, which is received within the reduced hub grammatic arrangementthe invention as embodied in Figs. 1 and 2.

Referring now to the drawings, the present in-- vention is here shown asapplied in connection with an hydraulic variablespeed transmission andfor purposes of illustration 1 have chosen to employ the hydraulictransmission shown in my Pa'tentNo. 2,086,535, issued July 13, 1937. Itwill be understood, however, that the invention may be used with anyother. type of hydraulic variable speed" transmission or other suitable'hydraulic a p u -1 7 As shown'in Fig. l of the accompanying drawingsthe. hydraulic transmission .comprises a 1 variable stroke pump Ahavingfluid connections 15 with an hydraulic motor B, the adjacent endsof said pump and motor being supported by and having fluid connectionsthrough an intermediate supporting member C.

The pump A comprises a hollow rotor i2 upon 20 which are carried aplurality of outwardly-dis charging radial cylinders 13 having fluidconnections through curbed hollow arms I 4 with ports in a reduced hubportion, not shown, of the rotor l2, saidports being adapted to registersuccessively with intake and exhaust ports'in a stationary trunnion-likevalve member, not shown. Each cylinder is flttedwith the usual pistonand .connecting rod assembly and theinner ends of the connecting rodsbear' against a laterally adjustable crank mechanism by which theirstroke may be varied from zero to maximumin either direction; thepistons, connecting rods and crank mechanism are not shown in theaccompanying drawings. Movement of the crank mechanism, in order toalter the stroke of the pistons, may be eflected by any suitable means.The rotor i2 is supported atone end by anappropriate supporting memberl5 and on the other end is' supported by the trunnion-like valve member,not

portion of the rotor l2. The valve member has an exposed flange I! whichis rigidly secured by anysuitable means to the member 0. The pump A isdriven by the shaft it which is attached tothe rotor I; in anyappropriate manner, and-the forward end of said pump A is enclosed byacover it which also forms part of the reservoir for I surplus fluid.

The hydraulic, B is" generallysimilar to the pump A except that it ishere assumed to have a fixed crank member sothat its pistons have acorresponding fixed stroke; the motor B may be made a variable'stroke ifdesired, how-- ever. It comprises a hollow rotor 20 having a 5 4 hubportion 2|, said ports being adapted to register successively with theintake and exhaust ports of the trunnion-like valve member, not shown,of the motor B. One end of this valve member is received within the hubportion 2| of the rotor 20 and on its other end is formed an exposedflange 24 which is rigidly secured to the member C, upon which theentire weight of the motor B is carried. The rear or outer end of therotor 20 is closed by a plate 25 having a shaft 26 which constitutes thedriven shaft of the hydraulic motor B.

Formed within the member C is a pair of longitudinal passages 21 and 28(Fig. 2) which connect with similar passages leading from one of theports of the trunnion-like valve member, not shown, of the pump A andwhich also connect with similar passages leading to one of the ports ofthe trunnion-like valve member, not shown,

of the motor B. Also formed within the member C is a pair oflongitudinal passages 29 and 30 respectively (Fig. 2) which connect withsimilar passages leading from the other of the ports of the valvemember, not shown, of the pump A and which likewise connect with similarpassages leading to the other of the ports of the valve member, notshown, of the motor B. It will be readily understood that these passagesform part of the closed fluid circuit between the pump A and the motorB. It will also be understood that when the device is in operationpressure fluid will pass from the pump A to the motor B either throughthe pair ofpassages 21 and 28 or the pair of passages 29 and 30,depending upon the position of the crank mechanism, and that fluid willbe returned from the motor B to the pump A through the other pair ofpassages. In other Words, whenever high pressure fluid is passingthrough the pair of passages 21 and 28, fluid exhausted by themotor Bwill be returned to the pump A through the pair of passages 29 and 30and vice versa. For convenience the portion Of the main fluid circuitcontaining fluid at the higher or working pressure is termed highpressure portion of the main circuit and the portion through which theexhausted fluid is returned from the motor to the pump is forconvenience termed the "return or low pressure portion of said circuit.7

As will be readily understood the hydraulic transmission hereinbeforedescribed is of the infinitely variable and reversible type. In otherwords, the stroke of the pump A may be made any desired amount fromminimum to maximum which will produce a corresponding speed of the motorB. Also the crank mechanism of the pump A may be shifted so that thepressure fluid from thepump A is, discharged into its valve port whichis connected with the pair of passages 21 and 28, causing the motor B torevolve in one direction; or the crank mechanism of said pump A may beshifted so as to cause pressure fluid to be discharged into its valveport connected with the pair of passages 29 and 30 causing the motor- Bto revolve in the opposite direction of rotation; e A

In any device of this class there will necessarily be some leakage ofthe fluid out or the main circuit and means are provided for collectingsuchleakage fluid and for returning it to the reservoir. As shown inFig. 1 the reservoir 32 is appropriately supported on the member 0 andextends to and is connected with the interior of the cover member l6 ofthe pump A which forms a portion of the reservoir for surplus fluid ashereinbefore stated. In the hydraulic transmission here chosen forpurposes of illustration the fluid leaking out of the cylinders of thepump A is collected in the casing of the rotor 12, whence it passes intothe interior of the cover I6 through suitable openings, not shown, inthe supporting member I5. Similarly, fluid lealn'ng out of the open endsof the cylinders of the motor B is collected in the interior of therotor 20, whence it passes out through an appropriate passage formed inthe trunnion-like valve member of said motor B, as indicated in Fig. 1by the dotted lines 33, which is connected with the reservoir 32 by theleakage return passage 34 in the member C. Fluid leaking from therunning joint formed by the trunnion-like valve member of the pump A andthe valve chamber formed by the hub of the rotor [2 may pass into theinterior of said rotor I2 and thence into the interior of the cover I 6and the reservoir 32 as hereinbefore explained; there are also providedhowever means for collecting any fluid leaking out of said running jointand passing toward the member 0, which includes an appropriate channel,not shown, suitably connected with the leakage return passage 34 as bymeans of a passage 36 indicated by dotted lines in Fig. 1. Fluid leakingout through the running joint formed by the valve member of the motor Band the hub portion 2| of the rotor 20 may pass either into the interiorof said rotor 20, and thence to the reservoir 32, or

may pass toward the member C and into an appropriate channel, not shown,which is suitably connected with the leakage return passage 34 as by thepassage 31 indicated by dotted lines in Fig. 1. It will be evident thatall fluid leaking out of the main circuit of the hydraulic transmissionis thus collected and returned to the reservoir 32.

There is also provided a small auxiliary pressure pump .40, which forconvenience I term a leakage pump. As shown in Fig. 1, the leakage pump40 is positioned in the lower end of the cover l6 and is suitablysupported as by the member IS. The leakage pump MI is driven by somesuitable means such as a chain 4| trained about a sprocket 42 of saidleakage pump 40 and about a sprocket, not shown, mounted on the drivingshaft In of the pump A. The arrangement is such that the leakage pump 40is continuously driven whenever the pump A is in bperation, thusassuring a substantially continuous delivery of pressure fluid by theleakage pump. The leakage pump 40 :may be of any preferred type,'such asthe well known gear pumP,.a-nd is preferably made of a capacity largeenough to supply an excess of fluid over and above the amount needed toreplenish the leakage from the main circuit. The suction side of theleakage pump is connected through an intake'pipe 43 with a supply offluid in the reservoir 32 and the cover I6 and the discharge side ofsaid leakage pump 40 is connected with a pipe 44 whose other end isconnected with a transverse'passage 15 formed in a distributing casingII, here shown (see Fig. '2) as positioned beneath the member C andabove the reservoir 32.

The distributing casing 59 is formed with vertical passages SI and 52(Fig. 2) respectively whose inner ends connect with'the transversepassage II. The passage II is provided cuit through the passages 54, 56and 58. Within the passages 5| and 52 are check valves-8| and 92respectively which are adapted to open to admit fluid from the passage45 into passages 53 and 54 respectively whenever the pressure in thecorresponding passage is less than the pressure in said passage 45 butwhich close when the higher pressure exists in said corresponding pas-"sages 53 or 54. It will be'understooclithat the check valves BI and, 92act independently of each other and that either one orboth of them maybe held open or closed at any particular time, depending entirely uponthe relative pressures in the passages 53 and 54 and in the passage 45.Also leading from the transverse passage 45 is a pipe 46 which connectswith a vertieal pipe 41 whose purposes will be explained la er.

The member C is also provided with a vertical passage 63 which isdrilled through from the top of said member C and which connects withthe longitudinal passage 29 and hence also 'has connection with thelongitudinal passage 89 v through the passage 58. The member C issimilarly provided with another vertical passage as which through thepassages 65, Gland 51 has connection with the pair of longitudinalpassages 2B and 21. The upper ends of passages 63 and 9d are closed inany suitable manner as by the plugs 57.

Located near the top of member C is atransverse passage broadlydesignated by the numeral. 19, which extends through the entire width ofthe said member C and intersects ,the vertical passages 93' and 69. Thepassage "I9 is formed with two end portions 1i and 12 respectively ofsubstantially equal bore and length, two reduced portions I3 and,respectively, also of substantially equal bore and length, two stillfurther reduced portions 15 and I6 respectively, likewise ofsubstantially equal bore' and length, and a. central counterboredportion ,1! connecting the portions 15 and I6. ,The arrangement is suchthat the passages 63 and 64 connect with the reduced portions 15 and 15respectively and the portion I3 and, 14 are connected with said passages63 and 64 respectively by'the passages I9 and 89.

The reduced portions 15 and 19 are adapted to serve as valve bores. forslidable valve members 8i and 82 respectively which are attached toorformed integrally with a reduced connecting link 83 of substantially thesame-length as the counterbore 11. The outer ends of the valves 8i and82 are provided with stems which act as guides for springs 85 and.respectively adapted. to act against theouter ends of said valves an dagainst washers-81 and 88 respectively. The washers 81 and 88 are heldagainst 4 the shoulders (formed by the ends of ,there-- duced portions13 and. 14 respectively) by means of heavier springs 89" and 99respectively, the other ends or, which act against suitable plugs"which'close the ends of the ipassage l9. (,Drill holes, not shown, areprovided in the washers the portions II and "and the portions 12 andvtionary element II.

14 respectively. Recessed within the peripheries 4 of the valves 8| and82 are V-shaped longitudinal grooves which extend from the outer end -01said valves to apoint intermediate of their inner ends.

The member C is also provided with a passage .58 which connects with thecounterbore 'l'l oi the horizontal passage 19 and whose outer end issuitably connected, as by a pipe 92,. with a passage. 93 formed in aunion member 95. The union member 95 is also provided with anotherpassage '94 whose inner end connects with the passage 98 and whose outerend is connected with the pipe 41. The outer enlarged'end or the passage93 connects with a passage III formed in the casing I I9 of the devicefor cleaning the fluid, to be described later.

Means are also provided for regulating the resistance to flow throughthe pipes 92 and 41 respectively, which in the present embodiment areshown as adjustable cocks 96 and 91 respectively, positionedintermediate the ends of said pipes and the union, member 95. Thecock9'l is pref erably, 'provided with a small bleed passage, not shown,or its adjustment limited to prevent its entire closure inorder thatthere may always be a path of escape for fluid delivered by the leakagepump 49. The purpose of these cocks is to regulate the relative portionsor the pressure fluid delivered by the leakage pump 59 that pass out ofthe distributing casing 5 through the pipes 49'and 4i and through thepipe 92 and its intervening connections.

The passages 93 and I II are closed by an exhaust or pressure regulatingvalve W9 which is positioned outwardly with respect to the passage 94and which is adapted to vary the opening so as to maintain asubstantially constant predetermined pressure in the portion of thecircuit intermediate said valve I09 and the leakage pump it. The valveI99 may be of any preferred type but as here shown is of an improvedtype which I preferto use in conjunction with my device for cleaning thefluid. As shown in Fig. 2, the exhaust valve i99 includes a stationaryelement I9! suitably fitted into an enlarged intermediate portion of thepassage 93 of the union member 95 and which is provided with a pluralityof passages I92 to'permit fluid to pass outwardly from said passage 99.The element mi is formed with a cylformed on the end of the element I95which projects into the intermediate enlargedend portion of the passage93 of the union member 95 and said flange I98 acts against one end of aspring I91 whose other end acts against the shoulder iormed' by theadjacent face of the casing H9. The element I95 is formed surrounds thecylindrical portion I83-0f-the sta- Fig. 2, of the bore I98 isconstricted in ,a shape substantially parallel with that of the pointedend of said element I9I, which isv adapted to close said bore I98 whenthe movable element is moved to its extreme position toward the leit, asviewed in Fig. 2. The jarrangement is such that fluid entering theintermediate enlarged portion of the passage indrical portion I93 whichterminates in a portion with abore I98 which The rightend, asviewed in93 passes through the passages III into the outer enlarged portion ofsaid passage 93,.and thence ment 5 is thus acted upon by the fluid andis moved toward the right a distance determined by the relative pressureof the fluid and resistance 'oflfered by the spring I". vThe spring I O1is preferably made such that the element II! is m moved. into a positionin which the constricted end of its bore I is closed by the pointed endof the cylindrical portion Ill whenever the fluid in the passage isbelow a predetermined amount, and the parts 01' the valve III arepreferably made such that the element ili moves to maintain, between theconstricted end of its bore Ill and the pointed end oi. the cylindricalportion ill, an opening substantially proportional to the volume offluid passing therethrough. in order m to maintain a substantiallyconstant rate of flow oi the fluid through said constricted end oi' saidbore Ill. a

The casing iii oi'my fluid cleaning device is substantially cylindricalin shape and is closed on 25 its bottom while its upper open end isclosed by a suitable cover 2. .The casing H is provided with athree-walled annularchannel i i3 open on its. inner side to the interiorof said casing ll! and positioned below the passage l I I i The upper 5wall or the channel I ll projects inwardly to form an annular flangewhich forms the support for the rim of the removable internal coverrl IIwhose hollow hub-like portion projects downwardly into 7 said casingill,

located centrally within. the casing III is a spindle llfl mounted foreasy rotation upon a suitable support in a seat Ill in the bottom oisaidcasing ill andheldinasubstantlallyvertical position by anotherappropriate support in a seat 4 H! in the cover ill. To'thevspindle-lll,at a point near its upper end and above the internal cover III. areattachedvanes III which are securely fastened tosaid spindle by anysuitable means. The vanes III are so formed and posi- 45 tionedthatfluid exhausted through the nos-ale formed by the constricted end ofthe valve Ill willimpingeagainstthemandcausethem thus rotating thespindle III. For case 0 assembly, the vanes I" may be convenientlyformed in with or attached to a hub slidkeyed in any appropriate manner.

*Aisolocatedfwithinthecaainglllisahcllow= cylinder |:'|,--m shown asopen on both its ends.

a I: desired, theiowerendb! thecylindei' flimbeprovi'dedwithabottomhavlngmpreierably near the center, of such sizeand ahapeas to eldflypcrmitthedownwardflowoifluid cylinder Ill. Thecylinder Ill issecurelyattaehedtothespindle li'Horsin'mltane-' ous'rotation therewith, as bya'rms I22.

lleansare also Provided Hor'alteringthe perature oi the'fluid and ashereshown comprises a conventional radiator ill having an inlet con- 63nectedwithaelllleadingiromthechanhe] 3. The radiatonlti is-likewiseprovided ,withanoutlet;heresliownaspositionednearits bottom.-which isconnected with the pipes III;

.mandilIlwhich-lead to the interior of the reservoir 29-30 or in the wably fitted on thesplndle Ill and adaptedto be ing correspondingreference mnnerals in the embodimentillustratedinmlandz.

' The. operation of the device is as follows:

When the machine stands idle, and there is consequently substantially nopressure in either 5 of the pairs of longitudinal passages 21-28 and eII 0! the distributing casing 50, the check valves I and I2 will-be heldclosed by their springs. Likewise the valve II, the link 83 and thevalve 82 are held in their 10 central position, as shown in Fig. 2, bythe springs 85 and I. which serve to center said valves with respect tothe counterbore The colmterbore I1 is then cut ofl from 'communica'fipnwith both of the valve bores and I6 by the valves Ii and 15 82respectively, and hence is also cut oil from communication with thepassages 63 and it so that no fluid may escape through them from eitherof the pairs of passages 2'|2l'or IHI.

The portions 13 and II of the passage II have a go fluid connection,however, with the passage it through the V-shaped grooves on the valve8!;

' similarly the portions 14 and 12 have fluid connection ,with the e llthrough the V- v shaped grooves on the valve 82.

If the machine is'now started with the crank mechanism in its zerostroke pomtion, the leakage pump' ll will deliver pressure fluid throughthe intervening connections to the transverseelioithedistributingcasingil andwill so almost immediately build uppressure in it and l in the connected pipes andJ'I. As soon asthepressureinthe ell exceeds thepressure'in either or both of the pairs0! passages 21-2! or 20-3., the check valves il and/or 82 5.willopentoad mitpressureflmdfromthepassage Ii into said passages 21-2!and/or 20-" and thiswillcontinue untilthcpressureinsaid equalsthepressure in said passage 4!. Anyleakage that has occurred in eitheroi the o pairsoi passages 21-" orIQ-Ilandintheportionsotthemaincircmtconnectedwith them'willthusibequicklyrepknisbcdandthefluidisthen hroughtuptothepressuredeteiminedbythe setting of the exhaust valve Ill. Excess-fluidnotnecdedtoreplaceleakagewillbeexhausted throughthepipes llandlhtheunion member ll andthe exhaust valve llland will passthroughthefluidcleaningdeviceandintm radiator!whmceitwillreturntotbereservcir- I! tohre-drculatedbytheleabgepumpll. Iithecrank mechanism isnow--moved awayi'romitsaerostnteposltionandadjustedsothat thepairot I'l-Ilbecomepartoi'the highpr'essureportionoithemain circuit, the fll lidl'casureinsaidpassagesl'ldlwilleaceed insane meinthepair 01 20-;whlchwillthenbethelowpressureesconveylngbacktotbepumpAthefluidwhichhasbeen exhausted by themotor B.- Likewise thew brcssureinthe8,85,84,1landl2 will e'xceedthe'pressureintbecorrespondingpas-'aagesfl,ll'andll. 'Iheexcesspressure thusex'ertedbythefluidupontheouterendofthevalveltwlllcausesaidvalvelttheconnectingcf linkflandthevalvelltomovetotheleitas vtewedinl ig.2.' Theammmt'oisuchmovement will dependupon therelative pressures in the pairfoi'. II-Idand -3. respectively,

a .-.-u v.

PkrI, tbespringllunflltheatem otthevalveilatrikesflaewuherllwhichach 2140 'increamtbevalvefl'anditsconnectedmemberawillcontlmietomovetotheiemaaviewedin lishes, communication between thepassage 83 and the counterbore 11 and fluid may pass from the pair ofpassages 29-30 through the passage 83, the valve bore 15, thecounterbqre 11, the passage 88and out through the pipe 92. The passage64 (which is connected with the pair of passages 21-28) remains incommunication with the portions '12 and 14 of the passage through the V-shaped grooves on the valve 82 but said valve 82 10 closes the valvebore 18 and prevents the escape of any high pressure fluid from thepassages 21-28 into the counterbore 11.

' The parts will remain in substantially this position as long as theadjustment of the stroke of the pump A is such that the pair of passages21-28 contain relatively high pressure fluid, until and unless thepressure in said passages 21-28 and their connected portions of the maincircuit exceed the amount determined by the spring 89 when said spring89 will be compressed and allow the valve 82 and its connected parts tobe moved still farther to the left so that the inner ends of theV-shaped grooves on the valve 82 will he in communication with thecounterbore 11. High 25 pressure fluid from the passages 21-28 may then-pass into the counterbore 11 and thence through the interveningpassages into the passages 29-30 or out through the passage 88, the.pipe 92, etc. Excess fluid pressure in the passages 21-28, and

30 hence in the high pressure side or portion of the main fluid circuit,will thus be relieved. When thepressure inthe passages 21-28 falls tothe maximum determined by the spring 89, said spring 89 will move theparts to the right until would, if unaided, be substantially zero andhence I less than the pressure in the passage 45, so that the checkvalve 82 will be opened and permit fluid from said passage 45-to passthrough the passages 54 and 58 into said passages 29-80. As the passages29-30 are thus connected with the passage 45, however, the fluid in saidpassages and in their connected low pressure portions of the main fluidcircuit will therefore be maintained under substantially the samepressure as is determined-by the exhaust valve I00.

' When the crank mechanism is moved back to its zero stroke position thevalve mechanism returns to the position shown in Fig. 2. When the crankmechanism is adjusted so that the pair of passages 29-30 contain thehigh pressure fluid delivered by the pump A, the passages 21-28 willcontain the low pressure fluid which they convey back to the pump A fromthe motor B, and the operation of the valve mechanism is obviouslyreversed. I

The arrangement is'therefore such that whichever of the pairs ofpassages 21-28, 29-30, are at the time the high pressure passages arenormally cut oil from communication with the leakage circuit. Likewise,whichever of the pairs of passages 21-28, 29-30, are at the time thelowpressure passages re automatically connected with the counterbore 11 andhence 'with the outlet passage 88, the pipe 92; and thecorresponding'check' valve 8| or 82 opens'to admit'leakage the washer 81strikes its stop formed by the outer circuit pressure fluid from thepassage 45 in the distributing casing 50 into said low pressurepassages. The device also limits the maximum permissible pressure inwhichever of the pairs of passages 21-28 or 29-30 are at the timethe 5high pressure passages and hence limits. the maximum permissiblepressure in the entire portion of the main fluid circuitwhich isconnected with said high pressure passages, thus acting as a safetyvalve. 10

From the foregoing it will be evident that two. paths of flow are thuspresented to pressure fluid delivered by the leakage pump 40 into thepassage 45 of the distributing casing 50, one through the pipes 48 and41 and the other through the 15 low pressure passages 21-28 or 29-30, asthe case may be and their connected passages. The relative amounts offluid passing out through each of these paths will depend upon'and varywith the relative resistance to flow offered by each 20 of these paths,which resistance may be regulated by the cocks 98 and 91. Thus if thereis relatively little resistance to flow through the cook 98 and theconnected passages intermediate said cook 96 and. the passage 45, and ifthe cock 91 25 is adjusted to offer relatively great resistance,substantially all of the fluid entering the passage 45 will pass intothe passage 55 or 58 (whichever is at the moment connected with the low.pressure or return portion of the main fluid cir- 30 cult). Assuming forpurposes of illustration-that this fluid passes into the passage 55, itwill then pass into-the passage 21 of the main fluid circuit and willforce out through the passage 28, the outlet passage 88, etc., acorresponding quantity 85 of, fluid over and above the amount needed toreplace whatever leakage has occurred in the main fluid circuit.

As leakage will vary with operating conditions, sometimes very littleoccurring, and as the leak- 40 age pump 40 is preferably made of suchsize that it delivers an excess of fluid over and above the quantityneeded to replace leakage, there will be a substantially continuouscirculation of fluid through the low pressure portion of the main fluid45 circuit, and heated fluid from the main fluid circuit willcontinuously be forced out and will be replaced by relatively cool fluiddelivered from the reservoir 32 by the leakage pump 40. The heated fluidthus expelled will'be cooled as it passes 50 through the radiator I25.The amount of such exchange of cool fluid for heated fluid in the mainfluid circuit may be altered as the particular installationor operatingconditions require by vary-. ing the relative resistances offered, as bymeans 55 of the cooks 98 and 91, and maybe made practically any amountfrom zero to maximum. It will also'be evident that leakage is positivelyreplaced under pressure and that the low pressure I portion of the mainfluid circuit is maintained at a substantially constant predetermined,pressure as fixed by the setting of the exhaust valve The eflectivenessof the cooling thus made possible' will be readilyunderstood when it isconsidered that the main fluid circuit is usually of relatively smallcapacity as. compared to the quantity of fluid delivered by the leakagepump in a short interval of time. While these will vary relative to eachother with particular embodiments, 70 in practice it will often be foundthat the fluid in the, entire main fluid circuit will be changed andreplaced by cool fluid very frequently, in some instances at a' rate ofseveral times-per minute.

A small drop in the temperature of fluid passing 7;

in the main circuit will tend to rise to the highest point and in mostinstances this will be at the upper ends of the passages 63 and 54. Thistendency will be increased when themachine is start- 10 ed and thepressure of the fluid in one or both of the pairs of passages 21-48 or29'-.-4l and their connected portions of the maincircuit is brought upto'the amount determined by the setting of the exhaust valve I". Whenthe crank 5 mechanism is moved out of its zero stroke position and theexchange of fluid between the high pressure portion of the leakagecircuit and the low pressure portion of the main circuit takes place asalready explained, any air accumulated in the zoupper end of the lowpressure valve port will be immediately expelled and replaced by fluidfrom the leakage circuit; other air in the main circuit will besimilarly expelled, either alone or along with fluid from said maincircuit, as the exchange '2' continues. Non-compressible liquids, suchas oils, 'are ordinarily used in machines of this class and bestoperation is securedonly when the main circuit is free from all air andcompletely fllled with liquid. Theproblem of expelling air from the 80main circuit has presented serious difficulties in the past. 1

Fluid, equal to the quantity not needed to replace leakage in the maincircuit will be exhausted through the valve I and the nozzle formed bythe. constricted end of the bore I08 will cause this exhausted fluidtomove at an increased and relatively high speed. Such fluid will strikethe wanes III, causing them to turn and Hence to rotate the spindle IIIand the attached cylinder I; I. This fluid will then flow downwardly(assuming that oil or some similar fluid is used, as customary). throughthe hollow hub of the intemal cover I I5 into the rotating cylinder IIIand will in turn be set in motion and caused to rotate. Centrifugalaction thus set up will throw the heavier unclean portion of the fluid,particles foreign matter, etc., outwardly against the wall of thecylinder III so that dirt and other impurities will be separated fromthe fluid and the lighter clean fluid will pass out through the openbottom of the cylinder |2I into the interior of the casing H0. The fluidbetween the casing III and the periphery of the cylinder III will againbe set in motion and the cleaning of the fluid 55 by centrifugal forcewill thus be continued. the impurities tending tooling to-the interiorof the casing I It. The cleaner fluid will thenbe adjacent theperipheryof the cylinder |2I and-such fluid will overflow' into thethree walled annular channelj-l it through the space between the lowerwall p of said channel I]: and thecylinder I2I. Such fluid will thenpass into the passage I28 and into the radiator I25, where it will becooled and from which it will be returned through the pipes I21 and-I28to the reservoir 32.. it will be observed that the lower wall of thechannel II} forms an inwardly projecting flange which acts as'asafeguardagainst impurities from the'cylinder Ill into said channel ll, ahdthenceInto,

the radiator Ill and the reservoir 32;

While any other source oi power may beam-y nloyed to operate thecentrifugal cleaner, it will be evident that in the present said.

'centrifugal-cleaner is operated by excess fluid,

' corresponding passages I6, II and 83. may be will then be a lowpressure portion, closable- 'silreportion whenever-the araaou power isrequired for its operation asit utilizes energy that would otherwise bewasted. As the device operates substantially continuously when-' everthe main pump A is being rotated; the cleaning process is likewisesubstantially continuous.

It is to be understood that the foregoingis merely an o exemplifyingdisclosure and that 7 changes may be made in the apparatus without inthe same plane, they may be positioned in separate planesand may belocated at entirely diflerent parts or the main circuit; similarly, the

.15 positioned at different points of the main fluid circuit if desired.It is preferred, as shown; that a the inlet 5| and outlet 66 .(also '55,63) shall be disposed at diflerent points of the main circuit for thepurpose of causing the fluid from the leakage circuit to traverse aportion'of the main circuit. It will also be evident that certain partsof the device may be employed separately and that their use is notlimited to any'particular type oi! fluid circulatory system.

I claim: 1 1. l'nafluid pressuredeviceamaincirculatory system having twoportions either of which may be a high pressure portion and the other ofwhich means for the admission oi. fluid in each of said portions,closable means for the escape of fluid in each of said portions anauxiliary circulatory system connected with each of said 11 and exhaustmeans'and means for automatically opening the admission and exhaust,means connecting .said auxiliary circulatory system with whichever ofsaid portions of said main circulatory isat that time the low pressureportion.

.- 2. In a fluid pressure device, a main circulatory system having twoportions either of which may be the high pressure portion and the otherof which will then be the low pressure portion, on

- auxiliary circulatory'system, means for admitting into said maincirculatory system fluid of one ,7 relative temperature from saidauxiliary circulatory system and for continuously expelling from saidmain circulatory system into said auxiliary circulatory system fluid ofa second relative temperature and means for altering the temperature-ofsaid expelled fluid to nam relative temperature.

3; In a fluid pressure device, a main circulatory system having twoportions eitherjof which may be the highpressureportionandthootherofwhichwi'llthenbethelowpressureportioml varate for escape of fluid ineach of said portions and valve mechanism controllingtheescapeoi'fluidthroughsaidexhaustpasssges. so;

saidvalvemechanism cloflngbothofsaidexhaust passages when the fluidpressure in one oi: saidportions substantially equals the fluid pressurein the other of said portions and automatically opening the exhaustpassagein'whichever of said portionsbecomes at the time the lowpresfluid pressure in one or said portionssubstantiollyexceeds the fluim lathe other oqsaid portions. and am auxiliarycirculatory systemadmitting fluid di- (0 rectlytowhioho'veroftheportipmof themain ;4.Ina''pressuredevicaa-maincirculator! systemhsvinsah siprels'ureportionandaiow 1s areas-11 system having a high pressureportion and a low pressure portion, separate passages for the escape offluid from each of said portions and valve mechanism controlling theescape of fluid through said passages, said valve mechanism beingresponsive to the difference in pressure of the two portions toautomatically open the passage for the low pressure portion andresponsive to further increased difference between the presthe escape offluid from each of said portions and valve mechanism controlling theescape of fluid through said exhaust passages, said valve mechanismbeing responsive to the difference in pressure of the two portions toautomatically open the exhaust passage for the low pressure portion andresponsive to further increased difference between the pressures in saidportions to automatically oper the exhaust passage for the high pressureportion, an auxiliary circulatory system admitting fluid directly to thelow pressure portion of the main circuit and means for regulating thepressure of the fluid in said exhaust passages.

7. In a fluid pressure device, a main circulatory system comprisinginterchangeable outgoing and return circuits, escape passages leadingfrom said circuits, a valve mechanism responsive to close the passageswhen the pressure of the outgoing and return circuits are substantiallythe same, to open the escape passage of one circuit when that circuithas a lower pressure than the pressure of the other circuit and to openthe escape passage of the other circuit when the diflerence betweenpressures in the two circuits reaches a predetermined amount,intakes-leading into said circuits, an auxiliary pressure circuit andmeans connecting the auxiliary pressure circuit with said intakes whenthe pressure in the auxiliary pressure circuit exceeds the pres ure inthe intakes.

'3- In a fluid pressure device, a main circulatory system. comprisinginterchangeable outgoing and return circuits, exhaust passages leadingfrom said circuits, a valve mechani m 'responsive to close the exhaustpassages when the pressures in said circuits are substantially the same,to open the exhaust of one circuit when that circuit has a lowerpressure than the pressure of the other circuit and to open the otherexhaust when the pressure of the other ,circuit reaches'a predeterminedhigh pressure, intakes leading into said circuits, an auxiliary pressurecircuit, means connecting the auxiliary pressure circuit with saidintakes when the pressure in the auxiliary pressure circuit exceeds thepressure in the intake and a cleansing and cooling circuit into whichsaid exhaust passages lead.

9. In a fluid pressure device comprising outgoing and return circuits, asource of fluid. supply, means for supplying fluid from said supplyunder pressure directly to both of said circuits when the pressurestherein are lower than a predetermined value and for supplying fluidunder pressure to only one of said circuits when the relative pressureschange and means for permitting the exhaust of fluid from the last namedcircuit while fluid is being supplied thereto from said source.

10. In a fluid pressure device, a main circulatory system having safetyvalve mechanism limiting the pres ure therein, an auxiliary circulatorysystem including an auxiliary pump, two paths of flow for fluiddelivered by said auxiliary pump, in addition to leakage, one of saidpaths including a portion of said main circulatory system, and meansseparate from said safety valve mechanism .for regulating the relativequantities of fluid passing through each of said paths comprising fluidflow resistance regulating mechanism in at least one of said paths.

11. In -a fluid pressure device, a main circulatory system having twoportions either of which may be the high pressure portion and the otherof which will then be the low pressure portion, separate exhaustpassages for the escape of fluid in each of said portions, valvemechanism con-. 1

trolling the escape of fluid through each of said exhaust passages, saidvalve mechanism clo ing both of said exhaust passages when the fluidpressure in one of said portions substantially equal the fluid pressurein the other of said p'ortions and automatically opening the exhaustpassage in whichever of said portions becomes the low pressure portionwhenever the fluid pressure in one of said portions exceeds the fluidpressure in the other of said portion an auxiliary circulatory systemadmitting fluid directly to the low pressure portion of said maincirculatory sys tem and means for regulating the pressure of the fluidin said exhaut passages.

12. In a fiuidpressure device, a main fluid circulatory system havingtwo portions either of which may be the high pressure portion and theother of which will then be the low pressure portion, separate exhaustpassages for the escape of fluid in each of saidportion valve mechanismcontrolling the escape of fluid through said exhaust passages, saidvalve mechanism closing both of said exhaust passages when the fluidpressure in one of said portions substantially equals the fluid pressurein the other of said portions and automatically opening the exhaustpassage in whichever of said portions becomes the low pressure portionwhenever the fluid pressure in one of said portions exceeds the fluidpressure in the other, an auxiliary-fluid circulatory system including apump, means for ad-' mitting fluid from said pump directly to whicheverof said portions is at the time the low pres- I irrespective of thequantity. of: fluid escaping through the high pressure escape means ofsaid flrst circuit, said exchange means including means for admittingfluid from said second circuit into said flrst circuit, an exhaustpassage in the low pressure portion of said first circuit for the escapeof fluid therefrom into said section circuit and means controlling theescape of fluid through said exhaust passage, and means for regpassageof fluid from said second circuit into.

said first circuit, a fluid exhaust connection at a point removed fromsaid admission connection for the passage of fluid from said lowpressure portion of said flrst circuit into said second circuit andmeans controlling the passage of fluid through said exhaust connection,and means for altering the quantity of fluid admitted from said secondcircuit to said first circuit 'to alter the rate .of fluid exchangebetween the two circuits independently of variations in leakage make-uprequirements.

aol

4 mitting to said main circuit fluid from said auxil- 15. In a fluidpressure device having a'closed main fluid circuit and an auxiliaryfluid circuit,

a system for exchanging fluid between the two circuits comprising'meansfor continuously adiary circuit in excess of the quantity needed toreplace leakage from said main circuit and continuously expelling fromsaid main circuit into said auxiliary circuit fluid equal in quantity tosaid excess, and means for varying the amount v of fluid admitted tosaid ma'incircuit to regulate the rate of fluid exchange between the twomain circuit with interchangeable high and low circuits independently ofvariations in leakage make-up requirements.

16. In a fluid pressure device having a closed pressure portions, and anauxiliary circuit, a system forexchanging fluid between the two circuitscomprising means for continuously admitting to whichever portion of saidmain'circuit is at the time the low pressure portion thereof fluid fromsaid auxiliary circuit in excess of the quantity needed to replaceleakage from said maln' circuit and continuously expelling from the someportion of said main circuit to which said fluid is admitted fluid equalin quantity to, said excess, and means for varying the amount of saidfluid to regulate the rate of fluid exchange-between the two circuits.

1'7. In a fluid pressure device having a closed main circuit withinterchangeable high and low pressure portions, and an auxiliarycircuit, a system for exchanging fluidbetween the two circuitscomprising means for continuously admitting to whichever of saidportions 01' the main circuit is at the time the low pressure portionthereof fluid from said auxiliary circuit in excess of the quantityneeded to replace leakage:

from said'main circuit, and means for continuously expelling from thesame portion of said main circuit to which said fluid is admitted fluidfrom the supply circuit into the main circuit and the by-pass circuitrespectively.

19. In a fluid pressure device, a main fluid regulate the relativequantities of fluid pressure circulating circuit, a fluid supply circuitleading from a source of fluid supply to the main circuit, a by -passcircuit leading from the supply circuit to said source of supply and anexha t circuit leading from the main circuit, inclu valve mechanism forboth controlling the flow from the low pressure side of the main circuitthrough said exhaust circuit and'relieving excess pressure in the highpressure side.

20. In a fluid pressure device, a closed main circuit,'an auxiliarycircuit including an auxiliary pump, .two paths of flow for fluiddelivered by said pump, one of said paths including a portionoi' saidmain circuit and the other comprising a by-pass passage, means formaintaining substantially equal predetermined pressures in both of saidpaths, and separate means for regulating the relative quantities offluid through each of saidpaths comprising an ad;- justable fluid flowresistance mechanism in at least one path. HUGO A. CEN'I'ERVAIL.

